Monday, April 09, 2007

Octostruma -- using photos to sort to morphospecies

Last week I tackled the genera Octostruma and Eurhopalothrix. Originally I had three specimens of Eurhopalothrix and 51 specimens of Octostruma. I rechecked them all and decided that they were all Octostruma. So... how to identify Octostruma species? Brown and Kempf (1960) have a key, but it seems to be extremely out of date. Longino has a key to Costa Rican species on his website, but most of them are morphospecies. I decided to try something I've always thought about doing, but never really had the ability to do until now. I used my nifty little microscope camera to take quick and dirty photos of all of my Octostruma specimens (head, lateral, and gaster), and try to use these photos to help me with my sort.

I decided not to look at the reproductives and ended up with 3 photos each of 36 specimens. This took a couple of hours. Then I started to look at the photos. I pulled up all of one kind of photo (for instance, all of the head shots) into photoshop and tiled all the photos so I can see all of them at once. Photoshop has a nice feature that allows you to change the zoom and location of one photo, and then press a button and it will automatically change all of the opened windows to match the zoom and location of that one. At first, I was very disappointed as the photos are pretty blurry and it seems difficult for me to get anything useful out of them. But after awhile I started to see some patterns that are very obvious to me because I can see all of the specimens at once. I was able to pull out a couple of specimens that were clearly distinct from all of the other ones. One has face sculpture that is longitudinally rugose whereas all the other ones have faces that are more clearly punctate. One has a ton of hairs on its thorax whereas all the other ones have between zero and four. And there are a couple of specimens that are clearly larger than others. I was able to move the photos around to group them with like photos and test out my ideas of what may be important. I ended up with eight morphospecies (not counting reproductives) which I am pretty happy with. I was even able to put a name on one of them.

I will post the descriptions soon, but wanted to get this entry out. I found the whole process to be much less frustrating than the way I usually do it, which is to look at one specimen at a time and constantly go back and forth to check and recheck characters between specimens. I just find it difficult to keep those images in my head for very long. Being able to see them all at once made a huge difference to me. Obviously, you still have to look at the specimens in the microscope to verify things, but overall I was very happy with my little experiment.

Update: I have posted some of the photos I used, if anyone would like to see them.

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